The proposed research addresses the ability of brain blood vessels to adapt their responsiveness, local blood flow and architecture to alterations in the cerebral cortex during cortical development, in response to neural activity, and after sensory deafferentation or deprivation. We use the well established model system, the whisker-- barrel cortex of the rat. This collaboration combines the complementary talents and resources of cerebrovascular laboratories in the Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences, St. Petersburg, Russian Republic, USSR, and in Washington University, St. Louis, Missouri, USA. This proposal will expand and enhance two research projects funded by NIH: (a) ROlHL41075 "Models for brain angiogenesis", and (b) R01 NS28781 "Imaging brain blood vessels during cortical activity". It will facilitate collaborative and correlative research on local cerebral blood flow, P02, evoked activity, angiogenesis, and vascular remodeling. Methods for videomicroscopy in vivo, fluorescent tracers, and histology of the barrel cortex of rodents are well established in St. Louis. The laboratory in St. Petersburg provides expertise in biophysical measurements of local cerebral blood flow (ICBF), extracellular fluid space (ECS), and tissue P02, using the same barrel cortex model. The expected results will include the correlation of physiological and videomicroscopic parameters in normal barrel cortex of rats and remodeling of cerebral blood vessels during development and after selective sensory deafferentation.